Precision dispense pump

Abstract

Precision dispense pumps comprise a housing that has an internal chamber disposed therein. A pressurizing assembly disposed within the chamber and includes a cylindrical pressurizing member having a head, a thin-walled skirt extending axially away from the head, and a flange is positioned circumferentially around the skirt. The pressurizing assembly includes a support coupled to backside of the pressurizing member. The support has a cylindrical outside surface sized support the skirt when it is translated from a chamber surface during pressurizing assembly axial movement. A shaft projects through an opening in the support and into a partial opening in the pressurizing member. A fluid transport body is attached to the housing and includes a fluid chamber having a fluid inlet port and a fluid outlet port. An actuator is disposed within an actuator housing attached to the housing and is coupled to the shaft to cause axial movement of the pressurizing assembly within the housing chamber. The pump can includes a vacuum assist element connected to the housing to provide a desired pressure differential within the pump to bias the skirt against supportive chamber or support surfaces during pressurizing assembly movement. Check valves are in fluid flow communication with the fluid inlet and fluid outlet ports to ensuring checked one-way passage of fluid into and out of the fluid chamber during respective intake and output strokes of the pressurizing assembly.

1. A pump comprising:
 a housing having an internal chamber disposed therein extending from a first housing end to a second housing end; 
 a pressurizing assembly axially movably disposed within the chamber comprising:
 a pressurizing member having an imperforate head positioned adjacent the housing first end and a thin-walled skirt extending circumferentially around and defining an edge of the head, the skirt having a desired axial length and having a flange positioned around a peripheral edge of the skirt, the pressurizing member having a backside surface including an opening disposed partially therein; 
 a support coupled to the pressurizing member backside surface and having a cylindrical outside surface that is sized to accept placement of the skirt thereon; 
 
 a shaft projecting through the support and into the pressurizing member opening, the shaft being coupled to the pressurizing assembly; 
 a fluid transport body attached to the housing first end and comprising a fluid chamber therein that includes a fluid inlet port and a fluid outlet port, wherein the pressurizing member flange is interposed between the body and the housing; 
 an actuator housing attached to the housing second end and comprising an actuator disposed therein for moving the shaft to cause axial movement of the pressurizing assembly within the housing chamber; 
 means connected to the housing for maintaining a desired positive pressure differential within the pump between the fluid chamber and housing chamber to provide a desired pressure force on the skirt to bias it into contact against a supportive surface of the housing chamber or support during pressurizing assembly axial movement; and 
 check valve means in fluid flow communication with the fluid inlet and fluid outlet ports to ensure checked one-way passage of fluid into and out of the fluid chamber during respective intake and output strokes of the pressurizing assembly; 
 wherein axial movement of the pressurizing assembly is facilitated by rolling movement of the pressurizing member skirt between adjacent concentrically positioned surfaces of the housing chamber and the support. 
 
   
   
     2. The pump as recited in  claim 1  wherein the actuator is provided in the form of an electric motor having a rotary shaft that is coupled with the support such that rotational movement of the rotary shalt causes the support and pressurizing member to move axially within the housing chamber. 
   
   
     3. The pump as recited in  claim 1  wherein the means for maintaining a desired pressure differential comprises a port disposed through the housing into the housing chamber, and wherein the port is connected to a vacuum source to impose a desired level of vacuum within the chamber. 
   
   
     4. The pump as recited in  claim 1  wherein the check valve means are poppet valves that are actuated to provide open and closed service during pump operation. 
   
   
     5. The pump as recited in  claim 1  wherein the pressurizing member and body fluid chamber are formed from non-metallic materials selected from the group consisting of fluoropolymeric compounds. 
   
   
     6. A precision dispense pump comprising:
 a housing having an internal chamber disposed therein extending from a first housing end to a second housing end; 
 a pressurizing assembly axially movably disposed within the chamber comprising:
 a pressurizing member having cylindrical outside surface, the pressurizing member having a one-piece constriction including:
 an imperforate head positioned adjacent the housing first end; 
 a thin-walled skirt integral with the head and extending circumferentially around and defining an edge of the head, the skirt having a desired axial length to provide a desired range of pressurizing assembly axial movement; and 
 a flange integral with the skirt and positioned circumferentially therearound to define a peripheral edge of the skirt, wherein the pressurizing member has a backside surface including an opening disposed partially therein; 
 
 a support coupled to the pressurizing member backside surface and having a cylindrical outside surface having a diameter sized to accept placement of the skirt thereon; 
 
 a shaft projecting through the support and into the pressurizing member opening, the shaft being coupled to the pressurizing assembly; 
 a shaft coupling member that disposed within the housing chamber and attached to the support, the shaft coupling member includes an opening disposed therethrough to accept placement of the shaft therein, wherein the shaft is movably coupled to the coupling member; 
 a fluid transport body attached to the housing first end and comprising a fluid chamber therein that is positioned adjacent the pressurizing assembly, the fluid chamber includes a fluid inlet port and a fluid outlet port, wherein the pressurizing member flange is interposed between the body and the housing to provide a leak-tight attachment therewith; 
 an actuator housing attached to the housing second end and comprising an actuator disposed therein having a rotary actuating member coupled to the shaft, the shaft being coupled to the shaft coupling member so that such that rotation of the shaft causes the axial displacement of the coupling member, connected support and pressurizing member within the housing; 
 vacuum assist means connected to the housing for maintaining a desired amount of pressure within the housing chamber that is less than that within the fluid chamber to provide a desired pressure force on the skirt to bias it into supportive contact against a adjacent concentric surfaces of the housing chamber and support during pressurizing assembly axial movement; and 
 fluid inlet and fluid outlet poppet valves in fluid flow communication with the respective fluid inlet port and fluid outlet port, the poppet valves being actuated individually to ensure checked one-way passage of fluid into and out of the fluid chamber during pump operation; 
 wherein axial movement of the pressurizing assembly is facilitated by rolling translation of the pressurizing member skirt between adjacent concentrically positioned surfaces of the housing chamber and the support. 
 
   
   
     7. A method for dispensing a precise amount of fluid comprising the steps of:
 actuating a pump pressurizing assembly disposed within a pump housing into an intake stroke to draw a predetermined volume of fluid into a fluid chamber of the pump, the fluid entering the fluid chamber via passage of the fluid through a fluid inlet valve that has been actuated to facilitate the passage of fluid to a fluid inlet port in fluid flow communication with the fluid chamber, the pump pressurizing assembly comprising a cylindrical one-piece pressurizing member having a head and a thin-walled skirt extending around the head and extending axially a distance therealong, a flange is positive along a peripheral edge of the skirt and is fixed to the housing; 
 actuating the pump pressurizing assembly into an output stoke to dispense the predetermined volume of fluid, the fluid exiting the fluid chamber via passage of the fluid through a fluid outlet port to a fluid outlet valve that has been actuated to facilitate the passage of fluid for dispensement from the pump; and 
 maintaining a desired pressure within the pump housing that is less than that in the fluid chamber to ensure that the pressurizing member skirt is biased against supporting wall surfaces within the pump during the actuating steps. 
 
   
   
     8. The method as recited in  claim 7  wherein the steps of actuating comprise operating an actuator that is connected to a shaft that is coupled to the pressurizing member, the actuator having a rotary member that is attached to the shaft, and the shaft being coupled to the pressurizing member to translate rotary shaft movement to axial pressurizing member displacement. 
   
   
     9. The method as recited in  claim 7  wherein the during the steps of actuating, the fluid inlet and fluid outlet valves are poppet valves that are independently actuated to facilitate respective inlet and outlet flow of fluid to and from the fluid chanter that is timed to correspond with the pressurizing member respective intake and output strokes. 
   
   
     10. The method as recited in  claim 7  wherein during steps of actuating, the pressurizing assembly is displaced axially within the housing by transition of the pressurizing member skirt from a first wall surface in the housing to a second concentrically positioned wall surface, and the skirt has an axial length that is sufficient to provide a desired degree of pressurizing member stroke length within the housing. 
   
   
     11. The method as recited in  claim 7  wherein the step of maintaining a desired pressure is provided through a port that is disposed through the housing and that is in communication with a vacuum generating means.